A Year at the Shore

by Philip Henry Gosse

The fecundity of these mollusca is immense. An Eolis papillosa of moderate size in one of my aquaria, deposited successively nine strings of spawn between March 20th and May 24th. The strings were exactly alike in length and arrangement; each comprised about 105 convolutions, and each convolution 200 eggs, while each egg contained on an average two embryos. Thus the astonishing number of 378,000 embryos proceeded from this one animal in about two months.

Step by step we have crept along the beach, turning stones as we went, till we are come to the great masses of sandstone rock. Here are the Purples[21] by hundreds, with their strong massive shells, some of them pure white, which, however, becomes dingy with age, some banded with brown, and some, especially the young and half-grown ones, painted with a dull but soft purplish hue. The older specimens have the inner surface of the lip tinged with a rich rosy purple. This tint on the shell we may receive as the advertisement of the colorific property that resides within, a sort of sign-board to tell us that this is the “genuine” purple-shell. And there is little doubt that it is one of those enumerated by Pliny, as used by the ancients for obtaining the renowned dye of Tyre: though the principal, and that which yielded the richest hue, was probably the Murex trunculus, a common Mediterranean shell, which does not extend to our shores.

Plate 5.
P. H. GOSSE, del. LEIGHTON, BROS.
LIMPET. PURPLE. SLIT-LIMPET.

My readers are, I dare say, familiar with the pretty myth which professes to embody the discovery of the purple dye. The Tyrian Hercules was one day walking with his sweetheart along the shore, followed by her lap-dog, when the playful animal seized a shell that had just been washed up on the beach. Its lips were presently dyed with a gorgeous purple tint, which was traceable to a juice that was pressed out of the shell-fish. The lady was charmed with the colour, and longed to have a dress of it; and, as wishes under such circumstances are laws, the enamoured hero set himself to gratify her, and soon succeeded in extracting and applying the dye, which afterwards became so famous. I have elsewhere[22] recorded my own experiments on the stain yielded by the Purpura before us, with the remarkable changes through which it passes before the sunlight fully brings out the colour. The use of cochineal makes us independent of molluscan dyes, and the matter is merely one of antiquarian interest, or a question of zoological chemistry.

EGGS OF DOG-WINKLE.

Perhaps you may be more interested in the development of the Dog-winkle. Under the ledges of rocks we find in abundance groups of little yellow bodies, resembling ninepins in shape, set on their ends in close contact with each other, and varying in numbers from three or four to a hundred or upwards in a group. Some of them are tinged with purple at the tips; and while sometimes you find them closed, and full of a yellow creamy substance, at others they are open at the top, and empty.

These are the egg-capsules of this mollusk, and some very unusual circumstances connected with the birth of the progeny, and their development within these cases, have been discovered by Dr. Carpenter.[23] Each capsule contains 500 or 600 globules that cannot be distinguished from each other at first; but only twelve to thirty of these are developed into young animals, though their united bulk ultimately equals that of the whole mass. The greater number of these globules are not real eggs, but only “yolk-spherules,” destined to afford nutriment to the true embryos, which greedily swallow them, after certain changes have taken place, and increase rapidly in bulk. It is curious, however, that they do not advance in development during this absorption of nutriment, but are, so to speak, arrested until a great augmentation of size is thus attained; then they quickly acquire the form of little free-swimming nautiloids, closely like those of the Doris and Eolis, a form which indeed is common to the early stages of all the known higher mollusca, however various may be their adult conditions.

LIMPET.